Sarah Shourd, one of three US citizens held in Iran for more than a year on suspicion of spying, has arrived in the Gulf state of Oman after being released on bail.

Shourd was allowed to leave Iran after around $500,000 was paid in Oman at Iran's state-run Bank Melli, Iran's English-language Press TV reported, quoting Abbas Jafari Dolatabadi, the Tehran prosecutor in charge of the case.

"Sarah Shourd has been handed over to the officials of the Swiss embassy in Iran, which represents US interests, after she was freed from jail," the prosecution website announced earlier.

"The case inspector informed the Tehran prosecutor about a bank guarantee concerning the posting of bail and, after the prosecutor's agreement, he issued the order for her freedom."

The US and Iran have had no diplomatic relations since the aftermath of the 1979 Islamic revolution.

Masoud Shafaii, Shourd's lawyer, said: "I left Evin prison with her. We signed her release forms and the last time I saw her was when she was on her way to the Swiss embassy."

Reunion in Oman

Shourd arrived in Muscat, the Omani capital, where her mother, Nora, who had travelled from the US, met her.

Nora told the AFP news agency last month Sarah was being held in solitary confinement despite suffering from a pre-cancerous cervical condition, a lump in her breast and depression.

Meanwhile, Iran's judiciary announced that the detention of Shourd's two US friends - Shane Bauer and Josh Fattal - had been extended for two more months.

Shafaii, Shourd's lawyer, said: "Sarah is extremely happy about her release but she urged me to help her two co-accused who are still in Evin prison."

In a statement welcoming Shourd's release, Barack Obama, the US president, said: "We remain hopeful that Iran will demonstrate renewed compassion by ensuring the return of Shane, Josh and all the other missing or detained Americans in Iran".

The three Americans were arrested near Iran's border with Iraq in July 31, 2009. Their families say they were on a mountain hike in northern Iraq at the time of their arrest.

Deep divisions

Shourd's case has highlighted deep divisions between Mahmoud Ahmadinejad, the Iranian president, and the judiciary.

The judiciary accused the government of pushing for her release, while some conservative politicans criticised Ahmadinejad directly for freeing her at a time when tension between Iran and the US is at its peak.

Dolatabadi, the prosecutor, strongly criticised the government on Sunday, saying "releasing information on judicial cases should not be done by government officials, and judicial authorities should handle it".

Ahmad Tavakoli, a prominent conservative politician, accused Ahmadinejad of pushing for Shourd's release, which would "intensify [US] pressure day by day" on Iran.